Tuesday, January 29, 2008

Damn You, Smartass. . .

. . . why didn't you tell me you were a physics genius? I went through two months of hell trying to get to the bottom of that goddamned 9/11 conspiracy story I wrote. Behold the dangers of Thinking Too Much: at one point, around two in the morning after watching way too many conspiracy videos, I actually thought: "Okay, so if I can just find out how many BTUs of heat it takes to weaken 110 stories' worth of steel, and how many BTUs are produced by an exploding jet plane and . . . holy shit, I'm in moonbat crazyland."

34 Comments:

smartass sob said...

"Damn You, Smartass..."

Ah. Music to my ears! ;-)

why didn't you tell me you were a physics genius?

Because I'm not. I'm just a simple tradesman who reads alot - and experiments alot. I can even weld two small pieces of steel together in a forge burning small chunks of wood for fuel - (although that is usually done with coal.)

I don't know if a thermite reaction actually took place in the Trade Center collapse, but the requisite materials were certainly there to leave the residue of one. And in any event conditions were right to severely weaken the structural steel. Given that and tons of concrete floors "pancaking" down it is no wonder the buildings fell as they did. Any bolts or other horizontal members would have been simply sheared.

Regarding BTUs it is not just the amount of heat produced that is important but it's concentration and time of release. For example: place a piece of paper in the sun on a hot day and the paper becomes warm - perhaps even hot - to the touch. Concentrate those same rays of the sun into a small area by focusing them with a lens and the paper will burn. The BTUs are roughly the same, but putting them in a small area produces a fast rise in temperature until the ignition point is reached. Another example would be a collection of oily rags. They oxidize creating heat (BTU), but if left in the open air, the heat dissipates harmlessly. However, if thrown in a trash can or left in pail, the heat does not dissipate - it can spontaneously ignite the rags.

Good point. But remember: it was two a.m. in the middle of a workweek after I'd watched several hours of conspiracy videos. My BTU thought was still more rational than most of what I was watching.

I must say, the online Flash video talking about how no plane hit the Pentagon has a kickass soundtrack (lifted from Fight Club). But its main "proof" was even dumber than its theory: plane crashes "mess up the ground," whereas the Pentagon's lawn is pristine.

Of course, plane crashes mess up the ground because they CRASH ON IT rather than FLY OVER IT on their way to HIT A GODDAMN BUILDING.

Personally, I think it's too bad that Jennifer didn't think to take advantage of the collective Peanut Gallery when faced with research. I'd volunteer to help with background, as I've bugged her for help on a couple things that needed a reporter viewpoint. I actually did answer a couple questions for one story because she knew about one of my interest/expertise areas, but it occurs to me that, per the title, she probably doesn't realize the resources available within the loyal phan club.

I'd say I could probably be of some measure of value when discussiong civil engineering, construction, electronics (HAM radio stuff I mentioned on another thread), general engineering 'stuff', firearms, a wee bit of military history but not too much, construction, reiki/chi kung/energy work, martial arts, financial accounting (have an MBA too..), finance, contracts, real estate (been through salesperson training, NOT a broker), and taoist sex practices, should that ever become a topic of discussion (I am actually serious 'bout that, but nuff said for now).

So who's got a database that can help her catagorize who to go for depending on what research is going on?

Not really about that, but thanks. I'd kind of prefer having hair back, being 30-40 lbs lighter, and changing "jobs" (iffin one could call it that) with Hugh Hefner sometimes, personally.

I'm being quite serious, I think Jennifer has one hell of a lot of good resources here, but being that it's the web where you don't really know people, she doesn't know what she has. If we had known she was getting wrapped around an axle, we might have saved a lot of time.

Nope, but she's gonna hook me up someday soon, and she won't be cussing me when it happens ;)

Given that and tons of concrete floors "pancaking" down it is no wonder the buildings fell as they did. Any bolts or other horizontal members would have been simply sheared.

Not necessarily. You're actually contradicting yourself here, to "pancake" the horizontal members had to stay roughly together, and the vertical members sheared. Secondly, the vertical members typically don't do this. There are a number of different failure mechanisms depending on what causes it, but we'll stick to a shear failure and a column failure for the purposes of this comment. Shear failures typically would result in a 45 degree angle at the connection, and the vertical members would be unaffected. I'm sure you recall the Oakland Expressway, remember the concrete columns all standing, sheared off at what approximates a 45 degree angle?

The second failure mode of a column is called Euler Column buckling, where residual stresses in the material create unbalanced stresses when subjected to an axial load, and cause a moment, or torque, to be created in the column itself. This causes the column to buckle outwards to a point where the applied moment exceeds the capacity of the member, and it basically fails like a beam, but due to an applied axial load instead of a transverse load (beam loading).

Neither of these is what I saw on the TV, and some videos. What I saw was basically a banana peel effect, where the outside structural members rotated rigidly outward and fell away, this pulled the next floor apart, etc. I haven't done a lot of looking at it, but to me this indicates that something in the horizontal was shearing, but not because of a "pancake" effect. It was propegating due to the outer skin pulling the next floor apart, etc.

I will admit that I'm surprised that someone hasn't published something looking at this, at the original design criteria. The fact that a couple of floors failed may have caused the top 1/3 of the building, or whatever part was above the failed floors, to collapse is one thing. The fact that it took the rest of the building down is another entirely. I don't honestly know if someone has looked at the connections and tension resisting capabilities of the horizontal members, but if I had someone killed in the building I would be pushing that.

The effect is the same, the mechanism is way different, I guess is what I'm saying. The buiding still ends up in a pile, and people end up dead. Your comments on the location and intensity of the heat are correct, but that applies only to the localized fire areas. The rest of the building, that doesn't apply.

Of course, realize that a fully loaded airplane is more than a couple pounds of added weight, and that alone could contribute a lot to overloading the structure. It has been a while since I've done multistory structural design, so I dont' know what kind of design loading they used, but I can pretty much gaurentee they didn't say "Ok, I'm going to add the weight of, say, a 727 right..hmmm..here!"

See here for a picture of what I'm talking about. Note all the columns are sheared at an angle, not straight across. There is a high geek factor reason for this, but I'll spare y'all in deference to Jennifer's already overtaxed brain cells holding this since Nov.

Good story Jennifer! Also, I hadn't ever considered the aluminum/magnesium composition of the aircraft fuselage before. Al/Mag is pretty common, and might be enough to ignite with iron/steel in a catastrophic event.

I have also done some blacksmithing, and as far as a black heat changing the composition of the crystalline structure of the steel, it is the cooling and tempering of the steel during and after the actual heating that is most critical, from my experience on a small scale. You can get steel to black heat and cool it many times before you see an appreciable difference in strength. Of course, I am not working with structural steels, and certainly not with thousand pound working loads. The variation in alloys is huge, and small changes make big differences.I would not think that simply heating a structural beam to a black heat would change its characteristics so much as to cause a failure. These beams are, after all, designed to withstand a fire up to a certain point. Was that point reached in the WTC towers? Ask an expert, not a hobbyist like me.

Heaven save my soul, Dangerman, if it turns out these people are right.

I am currently feeling very glum about some indignant e-mails I've received. I genuinely liked many of the people I spoke to for this story, and had no desire to hurt any of them, but. . . what was I to do?

These beams are, after all, designed to withstand a fire up to a certain point.

Actually, the fire rating comes from coverings around the steel, rather than the steel itself. Wood has a much better fire rating than steel, as it chars and tends to insulate the core.

I am currently feeling very glum about some indignant e-mails I've received. I genuinely liked many of the people I spoke to for this story

Then tell them that, and ask them to come on by (beats the hell out of Billy Dick, I mean Beck, if nothing else). Notice I've never said they're wrong, just pointing out a lack of focus. I'd think that if they come here they can throw out ideas, should be interesting if you're willing to put up with the bandwidth.

as far as a black heat changing the composition of the crystalline structure of the steel, it is the cooling and tempering of the steel during and after the actual heating that is most critical, from my experience on a small scale. You can get steel to black heat and cool it many times before you see an appreciable difference in strength.

Dangerman, I agree with you, but you're talking about heat-treating and permanent changes that occur - or at least, they're permanent until the piece is re-heated. What I was refering to is a temporary condition that occurs when steel is between 300 and 700 degrees fahrenheit. My old welding textbook (Modern Welding) calls it the "blue-brittle range" and warns against "peening" welds or other working at that temperature. There is also the old blacksmith's maxim that warns against striking steel that is at less than a red heat. Unfortunately my book doesn't explain why steel should be so brittle at that particular temperature range. Note that it is well below the transformation range and in fact, occupies only the middle of the black heat range. I do know that in my own experience I have had the misfortune of having a piece crack when I inadvertantly kept hammering it when it had cooled past red.Alex Bealer related in The Art of Blacksmithing that it used to be said that there were only two reasons for a blacksmith going to hell: One was for not charging enough and the other was for hitting blue steel.

Unfortunately my book doesn't explain why steel should be so brittle at that particular temperature range.

Must be something to do with how the atoms/molecules line up at that particular range. Similar to the way water swells when it becomes ice, because the molecules line up just so. I don't know how molecules in a "brittle" solid are linked together as compared to a stronger one, but . . . I just wanted to say something insightful and intelligent to gloss over my embarrassment in other matters here. Ahem.

Not necessarily. You're actually contradicting yourself here, to "pancake" the horizontal members had to stay roughly together, and the vertical members sheared.

Moose, what I actually meant by "pancake" was that after one floor fell it "sheared" or broke whatever connections were holding up the floor under it. And then those two floors fell on the next - and then three, and four etc.- until the force became virtually unstopable until it hit bottom. By horrizontal members I didn't mean the structural steel holding the floors themselves together - but whatever it is that attaches those floors to the central columns. Weren't those a "shear" failure - or is it called a tension failure or something?

I remember reading that the central columns also buckled or otherwise failed. It was theorized that the insulation covering them failed to protect them from the fire. I disremember whether it was because the insulation somehow got knocked off or because it failed from the heat.

And since you mentioned it, I too, recall seeing in the videos how the outer vertical members "banana-peeled" away from the structure. I had forgotten that. Actually there is quite a bit about those videos that I would like to forget; I still find them difficult to watch to this day.

That Euler Column buckling you speak of - I think I've seen that. I mean on a much smaller scale where a vertical member sometimes twists slightly before it bends and collapses under the weight it is supporting. Didn't know it had a name.

As regards the fire I read that it was not localized to a few floors near the planes, but that fuel had poured down the elevator shafts or some central part of the structures and was burning. Although the most intense heat would have been right there by the planes.

You know, what really surprises me about that whole catastrophe is the fact that the towers withstood the impact of the jet liners. I read or heard somewhere that the plan had been for them to topple and take out a great many other buildings - like falling dominoes.

I just wanted to say something insightful and intelligent to gloss over my embarrassment in other matters here. Ahem.

I don't see what you have to be embarrassed about. Perhaps it is some of conspiracy types who should be embarrassed. I still find it extremely difficult to entertain the notion that our own government might have been involved in the attack - or that "the Jews" arranged it. I just haven't seen any real evidence for the event happening in any significantly different way than what we've been told. Nothing that can't be explained anyway.

I mean on a much smaller scale where a vertical member sometimes twists slightly before it bends and collapses under the weight it is supporting. Didn't know it had a name.

That would be it. Steel is better than concrete in that regard as it's an engineered product, you have less material variation. However, a building as tall as WTC concrete isn't an option for a number of reasons.

For anyone who's interested here's a link to an excellent site where one can find answers for the questions raised by the conspiracy types as well as refutations of their assertions. Lot's of information about fires, thermite, molten metal, falling buildings etc. I found it over in the comments on Hit%Run's link to Jennifer's story. It's well worth reading some of it, if one has any interest in the matter.

Here's some info that might help explain that "banana peel" effect that you've mentioned

The money quote is the ref to gusset plates failing. Recall I said

I haven't done a lot of looking at it, but to me this indicates that something in the horizontal was shearing, but not because of a "pancake" effect. It was propegating due to the outer skin pulling the next floor apart, etc.

Failing gusset plates would cause this. There would be nothing holding the columns in any more.

I found it over in the comments on Hit%Run's link to Jennifer's story.

BTW, just where the hell were you when I was stuck trying to defend Jennifer to a rough crowd? Could have used some backup, but Noooooo, I was stuck out there by my lonesome. We'll see if you ever get a blog post dedicated to you again.

BTW, just where the hell were you when I was stuck trying to defend Jennifer to a rough crowd?

Which rough crowd? At H&R? or at The Advocate? I did a bit of defending at The Advocate. Didn't see you at H&R. By the time I read all the comments at the thread on H&R someone else had either already defended her a couple of times or the one guy that hadn't even read her full article had gone back and read it. How anyone could think she was taking sides, I don't know. Seemed like pretty balanced reporting to me. Besides - Jennifer is a regular poster at H&R and usually handles herself quite well; I hesitate to horn in on her behalf at that site - she mightn't appreciate it. Didn't see her there either.Do you post under A. Moose at Hit&Run?

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Failing gusset plates would cause this. There would be nothing holding the columns in any more.

One thing that never occured to me - not that I've done alot of thinking about it - was the effect of heat expansion of the various steel members in the towers. While it would take quite a bit of heat to make them expand, it would not take a really, really high temperature. I'm sure some allowance for expansion must be designed into the structure, even enough to allow for a normal building fire - or I would hope there is. I'm just wondering what the limits of that allowance would be and how much heat it would take to exceed them.It's an interesting site and I plan to do more reading over there. In particular, what he had to say about finding pools of molten steel weeks after the collapse and the explanation for them I found fascinating. It reminded me of admonishments I received as a kid against storing rusting steel wool; it actually can spontaneously ignite under the right conditions. Later.

But that's all it takes. Now some teeny-weeny little lizard person will come and snatch you away with his ship's tractor beam and abscond with you to Alpha Centauri where they eat our kind for dinner. Meanwhile all evidence that you ever existed will be wiped out by means of particle beam weapons and thought rays. The very memory of you shall be removed from the minds of the population - except, of course, for those of us who wear our special tinfoil headgear. Don't forget to write when you get to Alpha Centauri - I mean, if they don't devour you right away. :-)

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About Me

Jennifer Abel is an American writer who began her career in print media three minutes before the Internet killed the industry. After starting at a small Connecticut daily she moved to the Hartford Advocate, an alt-weekly where her journalistic coups included infiltrating a Furries convention and working on a phone sex line (which fired her six hours later). Since then she’s written for, or been reprinted in, dozens of print and web outlets, including Playboy, the Guardian, Salon, AlterNet, Mashable, the Daily Dot and pretty much every website with the words "cannabis" or "legalize it" in the title. Once, when she was young and naïve and needed the money, she unwittingly edited SEO copy for a spammer. However, in light of the spambot comments she’s deleted from her own blogs since then, she figures she’s more than repaid that particular karmic debt. Jennifer is currently looking for professional, non-spam writing jobs; interested editors are enthusiastically invited to e-mail her.